Abstract: In order to explore the characteristics and mechanism of agglomeration of clay particles in coal slurry water under the action of alkyl primary amine, the polar head base methyl primary amine cation (CH₆N⁺) of alkyl primary amine cationic is developed.The kaolinite and montmorillonite, 2 kinds of main clay matters in coal slurry water are taken as the object of study.The mechanism of adsorption of methyl primary amine cation on different clay surfaces is investigated through simulation and calculation based on density functional theory (DFT).Study result shows that:methyl amine cation can adsorb stably onto surfaces of the clay matters and form relatively stable configurations on kaolinite (001) surface, kaolinite (001) surface and montmorillonite surfaces with adsorption energies of -125.385, -140.96 and -299.31 kJ/mol respectively; and the adsorption mechanism of methyl amine cation is principally a result of the combined effects of electrostatic attraction and hydrogen bonding, with the former playing the predominant role.Experimentary study is also made of the characteristics of agglomeration of kaolinite and montmorillonite particles under the action of dodecyl primary amine (DDA) through surface wettability, zeta potential, agglomeration observation, adsorption amount and agglomeration sedimentation tests, so as to verify the DFT simulated result.As evidenced by test result, the adsorption of DDA on surface of clay particles can lead to improved hydrophobicity and reduced electronegativity of particle surface, which are helpful for clay particles to form hydrophobic agglomerates and speed up sediment of clay particles.